zmq_ppoll mostly mimics zmq_poll behavior, except for the added feature of being able to specify a signal mask. Signals in this mask will be blocked during execution of zmq_ppoll. Switching of the process' active signal mask happens atomically with the actual poll call, so that no race conditions can occur. This behavior is useful when one wants to gracefully handle POSIX signals without race conditions. See e.g. the discussion below https://250bpm.com/blog:12/ for an explanation.
Also includes two new tests:
1. test_zmq_ppoll_fd does the same thing as test_zmq_poll_fd, demonstrating backwards compatibility with zmq_poll when used with a default signal mask.
2. test_zmq_ppoll_signals demonstrates the use of zmq_ppoll with a signal mask, blocking out SIGTERM everywhere except in zmq_ppoll, allowing to handle the signal in one place without having to worry about race conditions.
Solution: switch to Github Actions
Travis recently started enforcing credits for OSS projects without
any funding. While it is possible to get free credits, it is a manual
step that involves contacting customer support via email and asking to
add them, every week. While this does not require money, it requires
something far scarcer: volunteers time.
Drop Travis and migrate to Github Actions.
* add opt-out for randombytes_close
Problem: randombytes_close is either a no-op or unsafe when a Context is running.
Unfortunately, there does not appear to be a single always correct choice,
so let builders pick between two not-great options.
Opting out can leak an FD on /dev/urandom which may need to be closed explicitly.
However, with the default behavior,
using multiple contexts with CURVE can crash with no application-level workaround available.
randombytes_close is not threadsafe and calling it while still in use by a Context can cause a crash.
For implementations using /dev/[u]random, this can leave up to one leftover FD per process.
The libsodium docs suggest that this function rarely needs to be called explicitly.
If you cloned and built this repo or built it from a submodule, it
would always report "Build and install draft classes and methods"
which first might be wrong if ENABLE_DRAFTS is OFF but also didn't
match the tense of other similar messages about build options.
The create_ipc_wildcard_address doesn't takes wide characters
into account while building a string from a temporary path.
The tmpnam_s can return a path in the user temp folder which
can contain special characters.
The string that is returned from the create_ipc_wildcard_address
will be used in the bind routine which will return an error code.
Retain GNU extensions for C99 and C++98 since testing old compilers
is especially difficult and these compilation modes exist to maintain
compatability.
When the build is performed with cmake option `-DPOLLER=select`, the following warning is triggered from 4 locations that import `polling_util.hpp`:
```
[...]/src/polling_util.hpp:115:50: warning: unused parameter 'pollset_' [-Wunused-parameter]
inline size_t valid_pollset_bytes (const fd_set &pollset_)
^
1 warning generated.
```
This is fixed here.
